1. Field of the Invention
The present invention generally relates to an organoboron polymer containing a carboranyl group, silyl or siloxanyl groups and alkynyl groups within the backbone of the organoboron polymer. These bis(silyl or siloxanyl)carboranyl alkynyl polymers of varying molecular weight are useful for making further thermosetting polymers and ceramics and are in themselves oxidatively stable at high temperatures.
2. Description of the Related Art
The recent literature reflects continuing major research efforts to advance fundamental knowledge in high temperature material design. See K. J. Wynne and R. W. Rice, Ceramics Via Polymer Pyrolysis 14 ANN. REV. NAT. SCI. 297 (1984).
In the search for high temperature oxidatively stable materials considerable attention has been given to polymers containing boron within the polymer. It has been known that the addition of a carborane within a siloxane polymer significantly increases the thermal stability of such siloxane polymers. Therefore, polymers having the following general formula have been manufactured: ##STR1## where x and y are positive integers, q and q' are integers from 3 to 16, CB.sub.q H.sub.q' C is a carboranyl group, and R.sup.3 and R.sup.4 are saturated, unsaturated, or substituted hydrocarbons. Whenever applicable, note that both representations, CB.sub.q H.sub.q' C and ##STR2## are used to represent either the ortho, meta or para isomers of the respective carboranyl moieties. Other similar manufactured polymers are polymers having the general formula: ##STR3## where y is a positive integer, x is a positive integer greater than or equal to 0 (x.gtoreq.0), v is a positive integer greater than 0 (v&gt;0, or v.gtoreq.1), and q and q' are integers from 3 to 16. When q=q'=10, these polymers are commonly referred to as D.sub.x or D.sub.x+v -F.sub.v+1, respectively. Another polymer among this class has the formula: ##STR4## referred to as D.sub.2 -F.sub.1. The thermal properties of these polymers are given by PETAR DVORNIC ET AL. in HIGH TEMPERATURE SILOXANE ELASTOMERS published by Huthig & Wepf Verlag Basel, New York (1990) on pp. 277 in FIG. 5.7 and on pp.282 in FIG. 5.12 and by Edward N. Peters in Poly(dodecacarborane-siloxanes) published in J. MACROMOL. SCI.-REV. MACROMOL. CHEM., C17(2) on pp. 190-199 in FIGS. 3,4,5,6,7,10 and 12. It is evident from these figures that the aforementioned polymers lose more than 15-20% of their weight when heated, in an oxidative environment, above 600.degree. C.
Other polymers that have been manufactured have the following formula: ##STR5## where R.sup.1 =R.sup.2 =Me, or R.sup.1 =R.sup.2 Ph, or R.sup.2 =Ph and R.sup.2 =Me and where y is a positive integer. These polymers also show a weight loss in excess of 15-20% in an inert atmosphere when heated between 600.degree.-1000.degree. C. Greater weight loss is expected in an oxidative atmosphere when heated to the 600.degree.-1000.degree. C. range. See Table II of Maghsoodi et al. in Synthesis and Study of SilyleneDiacetylene Polymers published in 23 MACROMOLECULES pp. 4486 (1996).
There are very few carborane-siloxane or carborane-silane polymers that show high temperature stability (weight loss &lt;15-20%) in an oxidative environment. Many of the carborane polymers manufactured are cited in various U.S. patents. Bee, for instance, the following commonly assigned U.S. Pat. Nos.: 4,946,919; 4,269,757; 4,235,987; 4,208,492; 4,145,504; 3,661,847; 3,542,730; 3,457,222; and 3,234,288. While the examples of carborane-silane or carborane-siloxane polymers cited are not all inclusive, a majority of the polymers cited exhibit a weight loss greater than 15-20% in an oxidative environment when heated above 600.degree. C. There is an established need for carborane-silane or carborane-siloxane polymeric materials that show high temperature stability where weight percentage loss is limited to 20% or less when heated in excess of 600.degree. C. in an oxidative environment.
In addition, a majority of the carborane-siloxane or carborane-silane or alkynyl-silane or alkynyl-siloxane polymers made by others show elastomeric properties rather than properties of more rigid polymeric products like thermosetting polymers or ceramics. Thus, in addition to thermal stability, there is also a need for polymers that behave more as thermosets and ceramics, upon further polymerization, and less like elastomeric polymers.